drm/amd/display: Implement fixed DP drive settings

[Why]
Currently there are use cases that require DP link to maintain fixed VS
and PE in HW regardless of what the sink requests. BIOS integrated info
table will specify whether we need to use the fixed drive settings, and
the drive settings to use.

[How]
Implement changes to parse the integrated info table and set the fixed
drive settings accordingly.
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c

@@ -2321,6 +2321,8 @@ static enum bp_result get_integrated_info_v2_2(
 
 	info->ext_disp_conn_info.checksum =
 		info_v2_2->extdispconninfo.checksum;
+	info->ext_disp_conn_info.fixdpvoltageswing =
+		info_v2_2->extdispconninfo.fixdpvoltageswing;
 
 	info->edp1_info.edp_backlight_pwm_hz =
 	le16_to_cpu(info_v2_2->edp1_info.edp_backlight_pwm_hz);

drivers/gpu/drm/amd/display/dc/core/dc_link.c

@@ -1660,6 +1660,14 @@ static bool dc_link_construct_legacy(struct dc_link *link,
 				DC_LOG_DC("BIOS object table - ddi_channel_mapping: 0x%04X", link->ddi_channel_mapping.raw);
 				DC_LOG_DC("BIOS object table - chip_caps: %d", link->chip_caps);
 			}
+
+			if (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) {
+				link->bios_forced_drive_settings.VOLTAGE_SWING =
+						(info->ext_disp_conn_info.fixdpvoltageswing & 0x3);
+				link->bios_forced_drive_settings.PRE_EMPHASIS =
+						((info->ext_disp_conn_info.fixdpvoltageswing >> 2) & 0x3);
+			}
+
 			break;
 		}
 	}

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -1661,7 +1661,13 @@ static void override_training_settings(
 	if (overrides->ffe_preset != NULL)
 		lt_settings->ffe_preset = overrides->ffe_preset;
 #endif
-
+	/* Override HW lane settings with BIOS forced values if present */
+	if (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN &&
+			link->lttpr_mode == LTTPR_MODE_TRANSPARENT) {
+		lt_settings->voltage_swing = &link->bios_forced_drive_settings.VOLTAGE_SWING;
+		lt_settings->pre_emphasis = &link->bios_forced_drive_settings.PRE_EMPHASIS;
+		lt_settings->always_match_dpcd_with_hw_lane_settings = false;
+	}
 	for (lane = 0; lane < LANE_COUNT_DP_MAX; lane++) {
 		lt_settings->lane_settings[lane].VOLTAGE_SWING =
 			lt_settings->voltage_swing != NULL ?

drivers/gpu/drm/amd/display/dc/dc_link.h

@@ -178,6 +178,9 @@ struct dc_link {
 
 	struct psr_settings psr_settings;
 
+	/* Drive settings read from integrated info table */
+	struct dc_lane_settings bios_forced_drive_settings;
+
 	/* MST record stream using this link */
 	struct link_flags {
 		bool dp_keep_receiver_powered;

drivers/gpu/drm/amd/display/include/grph_object_ctrl_defs.h

@@ -328,6 +328,7 @@ struct integrated_info {
 
 		uint8_t gu_id[NUMBER_OF_UCHAR_FOR_GUID];
 		uint8_t checksum;
+		uint8_t fixdpvoltageswing;
 	} ext_disp_conn_info; /* exiting long long time */
 
 	struct available_s_clk_list {

drivers/gpu/drm/amd/display/include/link_service_types.h

@@ -117,6 +117,12 @@ struct link_training_settings {
 	bool enhanced_framing;
 	bool allow_invalid_msa_timing_param;
 	enum lttpr_mode lttpr_mode;
+
+	/* disallow different lanes to have different lane settings */
+	bool disallow_per_lane_settings;
+	/* dpcd lane settings will always use the same hw lane settings
+	 * even if it doesn't match requested lane adjust */
+	bool always_match_dpcd_with_hw_lane_settings;
 };
 
 /*TODO: Move this enum test harness*/